see quickly last changes

[andrea]

Sometimes it would be nice to see visually what's the difference between
the buffer and the file, visually.

Maybe just a background color of the text that has been written to
buffer and it's not in the file would be nice.

Any idea? Could I maybe use something in VC for that (those files are
under VCS anyway).

If many lines are not saved we could also have a timeout, that only
keeps the last or change the background color to a lighter one (for
example).

Is there something like that already maybe?